The present invention relates to electrical connectors and, in particular, to a method for making an electrical connector employing flexible adhesive.
Silicone rubber compression connectors made with alternating layers of conductor and insulator material have been in use for making temporary and/or permanent electrical connections between two electrical circuit boards, such as conventional printed wiring circuit boards, for at least thirty years. Compression connectors and/or compression jumpers are so called because they are clamped to or otherwise compressed or held under pressure between the two electrical circuit boards for making electrical connection therebetween. These connectors have the desirable characteristic of being compliant and compressible due to the characteristics of the silicone rubber, and so can accommodate variations in flatness and tolerances of the contact pads on each of the circuit boards to which they make electrical connection.
Typical conventional compressible connectors are made using a silicone rubber dielectric matrix having conductors therein provided by compatible silicone rubber that is filled with carbon, silver, gold or other conductive material. The use of silicone rubber for both dielectric and conductors provides for proper bonding therebetween for mechanical strength. A thickness along the direction of electrical conduction of about 1 mm (about 40 mils) is typical, and such silicone rubber connectors are available from several suppliers, such a ZEBRA(copyright) elastomeric connectors from Fujipoly (Internet URL www.fujipoly.com) and Z-axis Connector Company (Internet URL www.z-axiscc.com).
Although the silicone rubber elastomeric connectors may be xe2x80x9cidealxe2x80x9d for some applications, the silicone rubber presents certain drawbacks and disadvantages. For example, uncured silicone rubber, e.g., silicone molecules, may leach out or otherwise come to be disposed upon electrical contacts and contact pads, thereby to caus problems in soldering, bonding or otherwise making reliable electrical connection thereto. A further disadvantage is that mechanical fasteners and/or clamps are necessary to make electrical connection to such silicone rubber connectors, which increases the cost of the use thereof both with respect to the cost of the connector and of the labor necessary to utilize it, but allows replacement and rework.
Conventional elastomeric compression connectors have been made by many techniques that can provide a suitably fine pitch (i.e. the center-to-center spacing of adjacent conductors) for conventional printed circuit board applications. At fine pitch, e.g., pitch as fine as about 2-10 mils (about 50-250 xcexcm), manufacturability becomes limited by the available electrically conductive filler materials that fill the silicone elastomer to render it electrically conductive. In fact, very few such elastomeric compression connectors are suitable for pitches less than about 6 mils (about 150 xcexcm), either because their current-carrying capacity is too small or because they are too difficult to manufacture.
Accordingly, there is a need for an electrical connector suitable for manufacture at fine conductor pitch while providing improved current-carrying capacity as compared to conventional elastomeric compression connectors.
To this end, the method of the present invention comprises
providing a plurality of elongated metal conductors of an electrically-conductive metal;
placing the plurality of elongated metal conductors in generally parallel spaced-apart spatial relationship;
filling the spaces between the spaced apart elongated metal conductors with a molecularly flexible dielectric adhesive;
drying or B-staging the molecularly flexible dielectric adhesive;
whereby the plurality of elongated metal conductors are embedded in the dried or B-staged molecularly flexible dielectric adhesive; and
cutting the dried or B-staged molecularly flexible dielectric adhesive and the elongated metal conductors embedded therein in a direction transverse to the elongated direction of the elongated metal conductors.